"The USPSTF concludes that there is moderate certainty that the benefits of PSA-based screening for prostate cancer do not outweigh the harms," says the Task Force report. "The USPSTF now recommends against PSA-based screening for prostate cancer in all age groups."

The PSA test is used to pick up cancers before symptoms occur, but many of these cancers are slow growing and would not become a problem in a man's lifetime.

Still, their detection results in men having surgery, radiation, or other treatments, which have side effects including, incontinence, impotence and bowel dysfunction.

"Up to five in 1000 men will die within one month of prostate cancer surgery and between 10 and 70 men will have serious complications but survive," says the Task Force report.

Meanwhile, it found mixed evidence on the benefits of screening. The Task Force reports that a US trial found no reduction in death from PSA screening, while a European trial found 1000 men aged between 55 and 69 would need to be screened in order to prevent one death.

"Assessing the balance of benefits and harms requires weighing a moderate to high probability of early and persistent harm from treatment against the very low probability of preventing a death from prostate cancer in the long term," says the Task Force report.

In 2008 it recommended against PSA screening in men aged 75 years or older (who are most likely to have prostate cancer but more likely to die of something else), but now says screening shouldn't occur in men of any age.

Saving lives

But Australian advocates of the test say the Task Force has misread the evidence and are concerned it's "sending the wrong message". They say if asymptomatic men as early as age 40 are tested this will help pick up prostate cancer at an early and treatable stage.

According to the Prostate Cancer Foundation of Australia around two-thirds of Australian men aged 40 to 74 have been given the Medicare-covered PSA test. He says testing will prevent 600 of the 3300 prostate cancer deaths expected this year.

"We must do some test to save patients' lives," says Dr Peter Ruthven, president of the Urological Society of Australian and New Zealand, whose members are involved in treating patients with prostate cancer. He notes the Task Force did not have any urologists on it.

Ruthven says if biopsies show a PSA-detected cancer is slow growing urologists now suggest it be actively monitored rather than routinely removed.

The Task Force estimates 90 per cent of men with PSA-detected prostate cancer undergo early treatment

But Ruthven says around 50 per cent of patients with such cancer still end up choosing treatment because they prefer to know the cancer has gone.

"[Patients] find it difficult to deal with the psychological burden of knowing they've had a cancer diagnosed," he says.

Evidence-based medicine expert Professor Alex Barratt says when an asymptomatic man has a PSA test it can open a "Pandora's Box".

"Being told you have cancer is a very scary thing for anybody to hear and so of course the natural tendency is to want to have treatment and unfortunately the treatments for prostate cancer have substantial side effects and that's the problem."

Impartiality

Barratt defends the Task Force's weighing up of the harms and benefits of screening. She argues it has the necessary expertise and is likely to be more impartial than those involved in treating prostate cancer.

"Clinicians may not necessarily have expertise in epidemiology and sometimes have financial relationships with screening technologies and laboratories," says Barratt.

And she says the closeness of clinicians to patients with life-threatening illnesses makes it harder for them to make the best decisions for the broader healthy population.

"Doing something that's going to harm far more men than it will benefit isn't a good idea just because it's the only thing we have right now," she says.

Professor Ian Olver of Cancer Council Australia also believes overdiagnosis and overtreatment due to PSA testing is a problem and supports the new recommendations.

Olver says the reason why there is such controversy over PSA testing is because people are weighing the benefits and harms of testing differently.

"Some people would do anything to save a few lives and that's a perfectly reasonable reaction, but if you are going to harm a lot of people in doing that you've got to be a bit more circumspect," he says.